Re: [dm-devel] [Lsf-pc] [Topic] Bcache

["Ted Ts'o" <tytso mit edu>]

On Wed, Mar 14, 2012 at 02:33:25PM -0400, chetan loke wrote:
> But you are not explaining why dm is not the right stack. Just because
> it crashed when you tried doesn't mean it's not the right place.
> flash-cache works, doesn't it? flash-cache's limitation is because
> it's a dm-target or because it is using hashing or something else?
> There are start-ups who are doing quite great with SSD-cache+dm. So
> please stop kidding yourself.

SATA-attached flash is not the only kind of flash out there you know.
There is also PCIe-attached flash which is a wee bit faster (where wee
is defined as multiple orders of magnitude --- SATA-attached SSD's
typically have thousands of IOPS; Fusion I/O is shipping product today
with hundreds of thousands of IOPS, and has demonstrated a billion
IOPS early this year).  And Fusion I/O isn't the only company shipping
PCIe-attached flash products.

Startups may be doing great on SSD's; you may want to accept the fact
that there is stuff which is way, way, way better out there than
SSD's which are available on the market *today*.

And it's not like bache which is a new project.  It's working code,
just like flash cache is today.  So it's not like it needs to justify
its existence.

Best regards,

					- Ted